Authorities in Hong Kong have told pro-democracy protesters to leave a camp in Mong Kok so it can be cleared.
Tuesday's operation comes as officials begin enforcing court orders, following complaints by residents and businesses about the disruption.
Protesters are not expected to resist the move, and some have already begun taking down their tents and barricades.
The activists have been on the streets since early October, demanding a free choice of leader in the 2017 election.
China says the people of Hong Kong will be able to vote for the chief executive from a pool of candidates approved by a Beijing-backed committee.
Protesters originally numbered in the tens of thousands but have fallen to a few hundred, while attempts by both sides to reach a compromise have gone nowhere.
Thousands of police are on standby, but Tuesday's clearance will be carried out by court bailiffs.
Hong Kong and the Beijing government say the protests are illegal, and there is growing public frustration with the disruption to traffic and business.
Last week there was little resistance from the protesters as bailiffs cleared barricades from the camp in Admiralty, near government headquarters.
Tuesday's operation is expected to focus on the area around Nathan Road and Argyle Street, a busy commercial and tourist district.
Most of the protesters told local media they would remain peaceful and not try to resist the move.
"I'll stay until the last moment. When they ask me to go, then I'll leave," William Yu, 20, told South China Morning Post.
Another protester, Ken Chu, told the paper he was prepared in case police or bailiffs used force.
Operations to clear and contain camps in recent weeks have sometimes led to clashes.
An attempt by police to clear an underpass near Admiralty in October led to accusations that officers had used excessive violence, after a video emerged of officers apparently beating a protester.
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